/*
 * Copyright 2007-2009 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. 
 * 
 * Project: gtinyurl
 */
package org.gnut.tinyurl.portlet.utils;

import java.util.HashMap;
import java.util.Map;

/**
 * 
 * @author tungt
 * 
 */
public class SingletonUtils {
	private static Map map = new HashMap();

	/**
	 * 
	 * @param clazz
	 * @return
	 */
	public static Object getInstance(Class clazz) {
		if (clazz == null)
			return null;
		synchronized (map) {
			if (map.containsKey(clazz.getName()))
				return map.get(clazz.getName());
			else {
				Object result = null;
				try {
					result = clazz.newInstance();
					map.put(clazz.getName(), result);
				} catch (InstantiationException e) {

				} catch (IllegalAccessException e) {

				}
				return result;
			}
		}
	}

	/**
	 * 
	 * @param className
	 * @return
	 */
	public static Object getInstance(String className) {
		if (className == null || "".equals(className))
			return null;
		try {
			Class clazz = Thread.currentThread().getContextClassLoader()
					.loadClass(className);
			return getInstance(clazz);
		} catch (ClassNotFoundException e) {
			return null;
		}
	}

	/**
	 * 
	 * @param className
	 * @param clazz
	 * @return
	 */
	public static Object getInstance(String className, Class clazz) {
		if (className == null || "".equals(className) || clazz == null)
			return null;
		try {
			Class c = Thread.currentThread().getContextClassLoader()
					.loadClass(className);
			return clazz.cast(getInstance(c));
		} catch (ClassNotFoundException e) {
			return null;
		} catch (ClassCastException e) {
			return null;
		}
	}

}
